The packages of this type, of which an example is illustrated in U.S. Pat. No. 3,443,093, generally comprise a sealed container of plastic material, paper or the like, which has dimensions allowing an easy introduction thereof into an oral cavity against the tooth portions to be X-ray examined.
After exposure, the X-ray film, which is normally coated with sensitive emulsions on both sides, must be processed with developing and fixing solutions so as to reveal and make stable the X-ray image. To perform such operations, generally it is necessary to tear the container and remove the film in a dark room.
Alternatively, the developing and fixing processing can be carried out in full light directly inside the package, when the container is provided with sacks or tanks which can be opened upon pressure and contain the necessary solutions. Examples of packages of this type are illustrated in U.S. Pat. Nos. 3,430,042 and 3,964,604.
In all these above-mentioned package types, the X-ray film is exposed to a direct radiation. As known, this involves long exposures of the patient and of the operator to the radiations, with all the dangers deriving therefrom.
To limit this drawback, particular emulsions having higher sensitivity characteristics are more widely used, but these do not give appreciable results and even worsen the photographic results by giving rise to low definition.
In the case of packages including the developing and fixing solutions, these drawbacks further comprise a process inconstancy which causes a further image worsening.
To remove such drawbacks, it has been proposed to adopt, as in other radiographic fields, film exposing techniques using an intensifying screen associated thereto. As known, such screens are treated with fluorescent materials which can emit light upon activation due to the exposure to radiations, in particular to X-rays. The light emitted by the fluorescent material exposes the light-sensitive emulsion in an extremely more effective way than direct exposure, thus appreciably cutting down the exposure times and/or the radiation quantity necessary to obtain a good image quality.
The employment of intensifying screens in X-ray film packages for dental use is known for instance from U.S. Pat. Nos. 2,049,447; 3,185,841; 3,419,719 and 3,433,950.
In these examples the intensifying screen is an integrating part of the package and is thrown away together with the container after exposure and processing (and removal for the examination) of the X-ray film. In other words, in all proposed solutions, the intensifying screen can be used only with the package, with which it is coupled, and therefore every single film requires its own intensifying screen.
This makes the package expensive due to the high cost of the screen materials.
Another drawback in all above mentioned solutions is that the intensifying screen must be applied to the package in absence of light to avoid alterations of the X-ray film characteristics and this requires complexed and delicate operations and, therefore, a further increase in the package cost.